Many kinds of scalpels are known and used in dental surgery practice. It is also known that dental scalpels designed for soft tissue surgery typically have thin, elongated handles adapted to hold a blade extending axially from the handle.
The typical surgical scalpel with handle and straight or angled blade can be used to remove excess material from the front (anterior) teeth, because in composite resin restoration of teeth there are often small ledges or overhangs present at the edges of the restorations. Such excess material must be removed from the surface of the tooth and from between adjoining teeth to provide a smooth, hygienic surface, but the anatomic considerations and limited accessibility prevent such an instrument from being used to remove the excess material from the bicuspid or molar teeth in the posterior segment of the mouth.
Many types of oral surgery (e.g. gingival operations, extraction of wisdom-teeth, etc.) cause specific access problems. In these cases it may be difficult to obtain access by means of a common straight scalpel. Sometimes it is necessary to use angled scalpels which are used, for example, in gingival operations.
The known scalpel by U.S. Pat. No. 6,413,265 provides a flat, fairly wide handle to be gripped between the distal phalanx regions of the thumb and the index finger only, and comprises a handle, a blade and a locking mechanism. The handle carries a short cusp blade positioned at acute angles to a horizontal plane (along to axis “X” of the axes coordinate “ZYZ”) through the handle and vertical longitudinal (“Y”) and transverse (“Z”) planes through the handle. The scalpels should be mostly used in pairs with one having a right angled blade and the other a left angled blade in order to enable the dentist to work with both the facial and lingual aspects of the teeth. The flat wide body of the handle is disposed along the horizontal plane. A vertical plane (“Y”) passes longitudinally through the handle, and the another vertical plane (“Z”) passes transversely through the handle. In accordance with this invention the blade is disposed at an acute angle with respect to the horizontal plane (“X”) and at an acute angle also with respect to one or both of the vertical axes (“Y”, “Z”). The blade is positioned at an angle with respect to the horizontal plane (“X”) of about between 55° and approximately 70°, about between 15° and 30° with respect to the longitudinal vertical plane (“Y”), and 60° and approximately 75° with respect to the transverse vertical plane (“Z”). The handle has a thickened front (or nose) region for securely retaining the blade in the handle. The nose of the handle is provided with an attachment mechanism, by which a blade can be secured to and removed from the handle. This mechanism may has the form of a stud protruding from the nose of the handle and having a non-circular head at its distal end. The blade is provided with an opening sized to slip over the head of stud. The blade is then rotated on the stud in order to engage a stop to become locked beneath the head of the stud.
This scalpel is in some aspects complex, considering the thickened nose region for securely retaining the blade in the handle and the presence of the opening, head and stud. Such scalpel is expensive because it is intended to be disposable, i.e., used on one patient and discarded and, and is not intended to be sterilized repeatedly. Also, the mentioned prior art is not enough elongated for the mouth difficult accessible areas.
Another known scalpel is described in U.S. Pat. No. 5,055,106. This scalpel includes a shank having a holder for releasably mounting a surgical blade. A ball of plastic material is formed by injection molding on the blade proper which consists of metal. The holder includes a sleeve, which is threadedly engaged with the shank at one end thereof and adapted to be screwed axially along the shank. The sleeve forms a ball socket, which is adapted to receive the ball of the blade therein. A clamping rod extends axially within the socket between the shank and the ball to engage and disengage said ball by the sleeve being screwed on the shank. The end of the clamping rod, which is adjacent to the ball, forms a circular sharp edge of a diameter which is smaller than the diameter of the ball, thus cutting into the plastic material of the ball when the sleeve is screwed to engage the clamping rod with said ball. More particularly, the surgical blade comprises a metal portion forming the actual blade (the knife edge), and on this metal portion a plastic body is formed by injection molding, said plastic body forming a neck and a ball. On the shank of the scalpel there is provided for the attachment of the blade a sleeve which forms a spherical ball socket available from the outside through a side aperture. The sleeve has a slot joining the aperture. The sleeve is threadedly engaged with the shank, and for this purpose the shank forms a thicker end portion with a bore having an inside screw thread. The sleeve having an outside screw threadedly engages the inside screw thread of the portion and is displaced axially into and out of the bore by the sleeve being rotated and thus being screwed on the shank. The clamp rod has at the end adjacent the ball socket a circular sharp edge, having a diameter which is smaller than the diameter of the ball. The other end of the clamp rod is engaged with an abutment surface formed by the shank at the bottom of the bore. The ball on the blade can is inserted into the ball socket passing through the side aperture. The ball is a freely rotatable in the ball socket for the adjustment of the blade to a desired rotated or angled position of the neck, being received by the slot at angling, and is locked with the blade in the desired position by screwing the sleeve axially on the shank so that the circular sharp edge of the clamp rod will be engaged with the ball and will cut into the plastic material of the ball. The hardness of the plastic material (e.g. carbon fibre reinforced plastic material) must be chosen such that it is lower than the hardness of the material of the clamp rod, (e.g. metal), so that it is possible for the edge of the clamp rod to cut into the material.
Such scalpel has the complex design (construction), has many components that creates the difficulties for satisfied sterilization (the dirt collected between components has to be thorough cleaned/removed), and inconvenient considering necessity of compatibility of the material hardness (e.g. the hardness of the plastic material /carbon fibre reinforced plastic material/ must be chosen such that it is lower than the hardness of the material of the clamp rod /metal/, so that it is possible for the edge of the clamp rod to cut into the material).
The other surgical cutting devices are well known in the medical practice. For example, U.S. Pat. No. 5,432,841, describes the surgical device comprising a handle, a blade rotatably mounted to the handle's distal end, and a controller on the handle for manually positioning the blade at a desired angular position during movement of the handle. More specifically, the surgical instrument comprises a handle, a latching mechanism, a controller and a blade. The handle includes two opposing walls joined at their proximal ends and separated at their distal end to form two blade holding jaws. The opposing walls of the handle are paralleled to each other. Also, the handle includes two platforms placed approximately two-thirds of the distance away from the distal ends on both walls, and a band placed between the jaws in order to prevent the jaws from separating a large amount. The band 24 (a metal spring) functions to prevent an excessive opening of the jaws in the disengaged position and serves to keep the walls in the proper orientation as they move past one another during the procedure. The band also acts as a spring which encourages the opening of the jaws in the disengaged position. It is the spring of metal band and the handle which is the opposing force to the latching mechanism providing a secure hold on the cylindrical shaft, which in turn secures the blade.
The jaws of the handle have two positions—a disengaged and engaged position. In the disengaged position the handle's jaws are held together before the handle engages the blade by a cap which is an auxiliary equipment and fits over the distal most tip portions of the jaws. Both jaws also contain orientation marks on their surface which helps align the blade with the handle. The orientation marks on the top surface of the jaws and form a straight line which is perpendicular to the long axis of the instrument when the instrument is in its engaged position. In use, the jaws are placed within the jaw cap, which allows the jaws to separate the proper amount so that the blade can fit up between their inner surfaces. The jaws are brought down over the blade in such a way that the orientation marks of the jaws form a line with the orientation mark on the top surface of blade. The orientation mark of the blade provides the proper placement of the blade into the jaws. The orientation marks on the jaws are placed at a distance from the distal end of the jaws which ensures the safe rotation of the cylindrical shaft of the blade between the inner surfaces of the jaws.
The latching mechanism consists of a slot, a receiver, and a securing member. The receiver is a rolling mechanism which consists of a cylinder and a bracket mounted on wall. The cylinder rolls on a pivot pin which is placed through the longitudinal axis of the cylinder and secured to each end of the bracket. The device also has some complex modifications described in the mentioned above patent.
This surgical device has the same deficiencies, i.e. the complex design (construction), has many components that creates the difficulties for satisfied sterilization (the dirt between components has to be thorough cleaned/removed), and inconvenient for surgeon considering its irregular form and necessity to change blade angle during surgical procedure.
The another scalpel with the adjustable blade is described in U.S. Pat. No. 4,672,964. The scalpel includes a handle, at the distal end of which is threaded a chuck housing, in which a chuck is adjustably held to the chuck housing and in which a blade is removably held. The chuck is arranged within the chuck housing to pivot within the range of a right angle or 90°, while the chuck and blade can rotate as a unit clockwise and counter-clockwise about the vertical axis (“Y”) of the blade. Also, the handle comprises the shaft, slot, crank head, retaining pin, groove, finger ridge, a locking rods, locking crank. The locking crank comprises a lever arm. The shallow recesses are formed in both the forward and rear edges of the crank head, respectively. The retaining pin passes through an enlarged hole formed in the crank head. Additionally, this scalpel has many other components (not described hereinto) coupled with the parts mentioned above.
The described surgical device is a complex and expensive scalpel requiring many controlling operations.
Thus, there is a great need in the art for the improved not complex, not expensive and reliable dental scalpel, providing the possibility of the convenient surgical procedure in the difficult accessible mouth areas.